The impact of having siblings - analysis of "hygiene theory" of chronic diseases in patients with type 1 diabetes in population of the Łódz region Hygiene theory and type 1 diabetes.

INTRODUCTION: In the recent years there has been a significant increase in the incidence of the type 1 diabetes mellitus. Therefore, numerous studies are underway to evaluate the possible factors underlying this trend. Some studies suggest that better sanitary conditions and lack of contact with microorganisms might be important, thus increasing the risk of disease in firstborns. Moreover, siblings could play an important role in the transmission of pathogens, which, by stimulating the immune system, may prevent the development of atopic and autoimmune diseases including such as type 1 diabetes. Current data, however, are still inconclusive.

PURPOSE: The aim of the study was to evaluate the effect of having siblings on the incidence of type 1 diabetes among children and adults.

MATERIALS AND METHODS: A group of 469 patients with type 1 diabetes was selected. The study population was composed of 245 adults and 224 youth patients. Information from Outpatient Diabetologic Departments database was gathered. Data such as age at the diagnosis of diabetes, sex of siblings, number and birth order were analyzed.

RESULTS: In the studied population, 4.5% were only children, and 30.3% patients came from large families. In the group of type 1 diabetic patients 39.7% were firstborns and this proportion was comparable to the group of healthy subject. The highest proportion of firstborns was noted in the group that was diagnosed after 18 years of age (45,1%) compared to the group that was diagnosed between 10 and 14 (29,1%) (p<0.05). Type 1 diabetic patients that were not firstborns much more often had older siblings of the opposite sex than the same sex.

CONCLUSIONS: he firstborns in the population of type 1 diabetes from the Łódz region did not outnumber the healthy subjects. Significantly higher proportion of firstborns in the group that was diagnosed after 18 years of age compared to the group that was diagnosed between 10 an 14 years was noted.